What the structural survey assesses
Five areas: (1) Structural loading capacity — the Building Engineer checks roof purlin sizing, spacing, and condition against the proposed ballasted or mechanically-fixed PV system dead load (15-20 kg/sqm ballasted, 5-10 kg/sqm mechanical). For modern logistics buildings (post-2000), loading reserve is almost always sufficient. For older buildings (pre-1990), structural calculation may reveal reinforcement requirement. (2) Roof material and condition — membrane type, age, warranty status, and any existing damage. Defects must be remediated before PV installation. (3) Sprinkler system clearances — LPC sprinkler clearance standards: 1m clear to deflector, 0.6m at high-bay spray heads. PV layout must respect these. Sometimes sprinkler heads require relocation (£2-15k). (4) Electrical infrastructure — main switchboard capacity, existing cable routes, substation access, point of connection for PV inverters. (5) DNO connection point — grid connection kV level, transformer capacity, metering arrangement.
Who carries out the structural survey
MCS commercial certification requires the structural survey to be carried out by or verified by a Chartered Structural Engineer (MIStructE/FIStructE or equivalent). The engineer produces a Building Engineer's Report (BER) which is the insurance and structural warranty basis for the installation. Our standard structural survey is carried out by a Chartered Structural Engineer and includes: roof loading calculations to British Standards (BS EN 1991-1-1 for dead load, BS EN 1991-1-3 for snow load, BS EN 1991-1-4 for wind load); roof material assessment; sprinkler clearance assessment; electrical infrastructure assessment. Survey cost: £750 (refundable against contract).
How to prepare your building for survey
Five preparation steps before structural survey: (1) Provide roof drawings — DWG or PDF structural drawings (including purlin schedule) if available. (2) Confirm sprinkler system type — installer needs to know if high-bay, standard, or ESFR (Early Suppression Fast Response) sprinklers are installed. (3) Arrange access to main electrical switchboard — our electrical engineer needs to inspect the main LV panel to assess connection point for inverters. (4) Identify asbestos register — if the building predates 1999, an asbestos survey should have been conducted and a register maintained. Our team must not disturb ACM (asbestos-containing materials). (5) Arrange safe roof access — our surveyors use roof access ladders or MEWP (Mobile Elevated Work Platform) — confirm which is appropriate for your building and who provides it.
What the survey output determines
The structural survey produces three key outputs: (1) Maximum achievable PV system size — the binding constraint is typically DNO grid capacity or structural loading, not roof area. The survey confirms structural ceiling. (2) Mounting system recommendation — ballasted (preferred for most membrane and profiled steel roofs, no penetration, preserves roof warranty) or mechanically fixed (lower dead load for constrained structures). (3) Pre-installation remediation — any roof defects, sprinkler head relocations, or electrical works that must be completed before PV installation commences. These are quoted separately and added to project scope if applicable.
Common questions
How long does the structural survey take?
Typically one full day on-site for a standard warehouse (50,000-200,000 sqft). Larger buildings (200,000-500,000 sqft) may take 1.5-2 days. The Building Engineer's Report is typically delivered within 5-7 working days of survey completion.
Do we have to pay for the structural survey if we decide not to proceed?
Survey cost is £750. If you proceed with installation, the £750 is credited against project cost. If you decide not to proceed for any reason after survey, the survey cost is retained — it covers the Building Engineer time and report preparation.
What happens if the survey reveals structural issues?
Two scenarios: (1) Minor issues (deteriorated roof sections, isolated sprinkler relocation) — we quote remediation and include in project scope. Typically £5,000-£50,000 range. (2) Major structural deficit — if the building needs reinforcement beyond a reasonable cost threshold, we discuss options with you. Sometimes part-roof installation at reduced scale is viable; sometimes the project economics don't justify reinforcement.